Project Summary/Abstract Current cochlear implants, while beneficial in their use, are limited in their capabilities by hand- assembly of the electrode arrays. This tedious manufacturing method is very costly, extremely labor- intensive, and inadequate in implementing new technologies for improving speech recognition and music appreciation. A superior alternative to hand assembly is microfabrication, which is a fully automated, low cost, and high yield manufacturing process that is capable of implementing a variety of innovations, including smaller array size for residual hearing preservation, drug delivery channels for inner ear health and cell regeneration, and strain gauges for improved performance during surgical insertion. Microfabrication is a very promising alternative to hand-assembly, but has yet to meet the following requirements for commercialization: (1) substrates must be composed of proven, long-term implantable materials (USP class VI), (2) electrode arrays must be compatible with standard surgical insertion techniques, (3) substrate and electrode sites must be able to withstand long-term electrical stimulation in the body, (4) the array must be long enough to extend from the tip of the cochlea to the location behind the ear where the electronics are implanted under the skin, and (5) the array must have electrical wiring that is compatible with the electrical feedthrough pins of the implantable cochlear stimulator (ICS). During Phase I, MEMStim showed that it is feasible to produce a microfabricated cochlear electrode array out of medical grade materials that can meet the commercial requirements (1) ? (3). The goal of Phase II will be to produce just such an array as a minimum viable product (MVP) for cochlear implant manufacturers. The MVP will address requirements (4) ? (5) and further improve upon the Phase I results of requirement (2). In order to accomplish the Phase II goal, the following Specific Aims will be accomplished: (Aim 1) produce a full length microfabricated cochlear array with an integrated cable that can be bonded to an implantable cochlear stimulator and complies with electrical, mechanical durability, biocompatibility, and FDA safety requirements specified in communications with cochlear implant manufacturers and (Aim 2) produce a connector scheme for integrating a microfabricated cochlear electrode to the feedthroughs of an implantable cochlear stimulator. The expected outcome is an array that can be integrated by customers into their cochlear implant systems and pass all handling/use/safety tests that cochlear implant manufacturers would need to seek approval from the FDA.